German Patent No. DE 196 26 576 describes an electromagnetically actuable fuel injection valve in which an armature coacts with an electrically excitable magnet coil for electromagnetic actuation, and the linear stroke of the armature is transferred via a valve needle to a valve closure element. The valve closure element coacts with a valve seating surface to form a sealing fit. Several fuel conduits are provided in the armature. Return of the armature is accomplished with a return spring.
The fuel injection valve described in German Patent No. DE 196 26 576 is disadvantageous especially with regard to relatively long closing times. Delays in the closing of the fuel injection valve are brought about by the adhesion forces acting between armature and internal pole, and because the magnetic field does not decay instantaneously when the excitation current is switched off. This results in metering times and metered volumes for the fuel that are worth improving. The generation of large closing forces by way of a high return spring force has the disadvantage of a high power requirement for excitation of the magnet coil. The output stage of an electrical control device must then be of correspondingly complex design.
The fuel injection valve according to the present invention has the advantage that the impact element joined to the valve needle converts the hydraulic momentum of the fuel, flowing in the spray-discharge direction through at least one fuel conduit in the armature or in the valve needle, into a more rapid closing motion.
The opening time remains largely unimpaired by the feature according to the present invention, since hydraulic flow is not yet present when the fuel injection valve opens. The faster detachment of the armature from the internal pole due to a momentum transfer from the fuel to the impact element results in shorter closing times for the fuel injection valve and thus in shorter fuel metering times and more precise metered fuel volumes.
It is advantageous to configure the impact element as an impact plate, since this shape is characterized by a low inert mass.
Also advantageous is the easy and economical manufacture of an integrally configured component comprising the valve needle and impact element, which can be manufactured, for example, as a turned part.